In 1989, asteroid 4179 was discovered by French astronomers and named
after a Celtic god that was the protector of the tribe in ancient Gaul.
Its eccentric, four-year orbit extends from just inside
Earth's orbit to the main
asteroid belt between
Mars and Jupiter.
The plane of Toutatis's orbit is closer to the plane of the Earth's
orbit than any known Earth-orbit-crossing asteroid.

In December 1992, Toutatis made
a close approach to Earth. At the time, it was an average of
about 4 million kilometers (2.5 million miles) from Earth. Images of
Toutatis were acquired using radar carried out at the Goldstone Deep
Space Communications Complex in California's Mojave desert. For most of
the work, a 400,000-watt coded radio transmission was beamed at Toutatis
from the Goldstone main 70-meter (230-foot) antenna. The echoes, which
took as little as 24 seconds to travel to Toutatis and back, were
received by the new 34-meter (112-foot) antenna and relayed back to the
70-meter (230-foot) station, where they were decoded and processed
into images.

The images of Toutatis reveal two irregularly shaped, cratered objects
about 4 and 2.5 kilometers (2.5 and 1.6 miles) in average diameter which
are probably in contact with each other. These "contact
binaries" may be fairly common since another one,
4769 Castalia, was observed in 1989 when it
passed near the Earth. Numerous surface features on Toutatis, including
a pair of half-mile-wide craters, side by side, and a series of three
prominent ridges -- a type of asteroid mountain range -- are presumed to
result from a complex history of impacts.

Toutatis is one of the strangest objects in the
solar system, with a highly irregular shape and an extraordinarily
complex "tumbling" rotation. Both its shape and rotation are
thought to be the outcome of a history of violent collisions.
"The vast majority of asteroids, and all the planets,
spin about a single axis, like a football thrown in a perfect
spiral, but Toutatis tumbles like a flubbed pass," said Dr.
Scott Hudson of Washington State University.
One consequence of this strange rotation is that
Toutatis does not have a fixed north pole like the Earth.
Instead, its north pole wanders along a curve on the asteroid
about every 5.4 days. "The stars viewed from Toutatis wouldn't
repeatedly follow circular paths, but would crisscross the sky,
never following the same path twice," Hudson said.

"The motion of the Sun during a Toutatis year,
which is about four Earth years, would be even more complex," he
continued. "In fact, Toutatis doesn't have anything you could
call a 'day.' Its rotation is the result of two different
types of motion with periods of 5.4 and 7.3 Earth days, that
combine in such a way that Toutatis's orientation with respect
to the solar system never repeats."

The rotations of hundreds of asteroids have been
studied with optical telescopes. The vast majority of them
appear to be in simple rotation with a fixed pole and periods
typically between one hour and one day, the scientists said,
even though the violent collisions these objects are thought to
have experienced would mean that every one of them, at some
time in the past, should have been tumbling like Toutatis.

Internal friction has caused asteroids to change into
simple rotational patterns in relatively brief amounts of time.
However, Toutatis rotates so slowly that this "dampening"
process would take much longer than the age of the solar
system. This means that the rotation of Toutatis is a
remarkable, well-preserved relic of the collision-related
evolution of an asteroid.

On September 29, 2004, Toutatis will pass by Earth at a
range of four times the distance between the Earth and the
Moon, the closest approach of any known asteroid or comet
between now and 2060. One consequence of the asteroid's
frequent close approaches to Earth is that its trajectory more
than several centuries from now cannot be predicted accurately.
In fact, of all the Earth-crossing asteroids, the orbit of
Toutatis is thought to be one of the most chaotic.

Topographic Map of Toutatis
This is a topographic map of Toutatis. It is based upon the shape model of Phil
Stooke which he produced using rendered images of the shape model by R.S. Hudson
and S.J. Ostro and modified by him to fit the radar images. As with all maps,
it is the cartographer's interpretation; not all features are necessarily certain
given the limited data available. This interpretation stretches the data as far
as possible.
(Courtesy A. Tayfun Oner)

Shaded Relief Map of Asteroid 4179 Toutatis
This is a shaded relief map of asteroid 4179 Toutatis. As with all
maps, it is the cartographer's interpretation and not all features are
necessarily certain given the limited data available. This interpretation
stretches the data as far as is feasible.
(Courtesy Phil Stooke, NSSDC, and NASA)

4 Views of Toutatis
This image shows four frames of asteroid Toutatis that were obtained on
December 8-10 and 13, 1992. On each day, the asteroid was in a different
orientation with respect to Earth. One large crater can be seen in the
December 9 image (upper right) that measures about 700 meters (2,300
feet) in diameter.
(Courtesy JPL/NASA)

Computer Model of Toutatis
These images show a computer model of the Earth-orbit-crossing asteroid
Toutatis. These views of the asteroid show shallow craters, linear
ridges, and a deep topographic "neck" whose geologic origin is
not known. It may have been sculpted by impacts into a single, coherent
body, or Toutatis might actually consist of two separate objects that
came together in a gentle collision.
(Courtesy Scott Hudson, Washington State University)

Spin State of Toutatis on Nine Successive Days
This image shows the non-principal-axis spin state of asteroid 4179
Toutatis at one-day intervals (from left to right, top to bottom).
The red, green, and blue axes are the principal axes of inertia; the
magenta axis is the angular momentum vector; the yellow axis is the spin
vector. Toutatis does not spin about a single axis. Instead, its spin
vector traces a curve around the asteroid's surface once every 5.41
days. During this time the object rotates once about its long axis,
and every 7.35 days, on average, the long axis precesses about the
angular momentum vector. The combination of these two motions with
different periods give Toutatis its bizarre "tumbling" rotation.
(Courtesy Scott Hudson, Washington State University)